Rainfall Measurements: How to Find Accurate Data for Your Area?

Finding Local Rainfall Data

To determine the average annual rainfall for your area, visit your local government’s website or contact your local weather office. They can provide you with historical climate data, including rainfall records for your specific location. For example, the National Centers for Environmental Information (NCEI) offers free access to historical climate data, including rainfall records for the United States.

Installing a Rain Gauge

A rain gauge is an essential tool for collecting on-site rainfall data. Consider installing a basic rain gauge, which can be purchased online or at a local hardware store, to collect rainfall data for your specific location. A standard rain gauge has a collection area of 4 inches (10.2 cm) in diameter and 10 inches (25.4 cm) in height. This size gauge can collect up to 1 inch (2.5 cm) of rainfall per hour, providing accurate data for cistern sizing.

Interpreting Rainfall Data

Once you have collected rainfall data from your on-site gauge or obtained historical climate data, it’s essential to interpret the results. Calculate the average annual rainfall for your area by dividing the total rainfall by the number of years. For example, if your rain gauge has recorded an average of 40 inches (101.6 cm) of rainfall per year over a 10-year period, your area receives approximately 4 inches (10.2 cm) of rainfall per month. Use this data to determine the required cistern size for your specific needs, taking into account factors like water storage requirements and intended use.